Disk cartridge

1. A disk cartridge comprising: a cartridge housing in which a disk compartment is formed between an upper shell and a middle shell or between said middle shell and a lower shell by overlapping said upper shell, said middle shell and said lower shell and in which said middle shell is rotatably supported by said upper shell and said lower shell; a disk shaped recording medium stored within said disk compartment so as to become freely rotatable; a pair of shutter members attached to said middle shell in such a manner that they can be moved in a flat surface direction on the same plane; and a shutter opening and closing mechanism for opening and a closing portion to be opened by moving said pair of shutter members based on the rotation of said middle shell, wherein said shutter opening and closing mechanism includes rotary coupling portions respectively provided on one side portions of said pair of shutter members and which are coupled to said middle shell so as to become freely rotatable and movement coupling portions respectively provided on the other side portions of said respective shutter members and which are coupled to said lower shell or said upper shell so as to become movable relatively and said shutter opening and closing mechanism opens and closes said opening portion by rotating said pair of shutter members around said rotary coupling members based on the rotation of said middle shell to thereby relatively move said movement coupling portions.

2. A disk cartridge comprising: a cartridge housing in which a disk compartment is formed between an upper shell and a middle shell or between said middle shell and a lower shell by overlapping said upper shell, said middle shell and said lower shell and in which said middle shell is rotatably supported by said upper shell and said lower shell; a disk shaped recording medium stored within said disk compartment so as to become freely rotatable; a pair of shutter members attached to said middle shell in such a manner that they can be moved in a flat surface direction on the same plane; and a shutter opening and closing mechanism for opening and a closing portion to be opened by moving said pair of shutter members based on the rotation of said middle shell, wherein an elevation mechanism for moving said middle shell in the direction perpendicular to said rotation direction based on the rotation of said middle shell so that said middle shell is pressed against said lower shell or said upper shell.

3. A disk cartridge comprising: a cartridge housing in which a disk compartment is formed between an upper shell and a middle shell or between said middle shell and a lower shell by overlapping said upper shell, said middle shell and said lower shell and in which said middle shell is rotatably supported by said upper shell and said lower shell; a disk shaped recording medium stored within said disk compartment so as to become freely rotatable; a pair of shutter members attached to said middle shell in such a manner that they can be moved in a flat surface direction on the same plane; and a shutter opening and closing mechanism for opening and a closing portion to be opened by moving said pair of shutter members based on the rotation of said middle shell, wherein a gear portion is provided on the outer peripheral surface of said middle shell over a predetermined range of the circumferential direction and an opening window from which a part of said gear portion is exposed is bored through the side surface of said upper shell and said lower shell.